A distraction of a lower extremity or in other words a pulling on a lower extremity, such as for example of a leg, is necessary for some surgical and diagnostic procedures, such as reducing a fracture of a bone of the lower extremity, hip arthroscopy, hip arthroplasty or an imaging procedure. Applying a tensile stress to parts of the lower extremity will allow parts of the lower extremity, such as for example the femur, the knee, the shank and the malleolus, to be brought into a position suitable for an operation or examination. The tensile stress may also be used to pull apart the joints which connect the limbs of the lower extremity in order to allow for an operation or an examination of the joints. The words traction and distension are used synonymously for distraction.
FIG. 1 shows a base support 1 which may be used for distraction of lower extremities 2 of a person 3. The person 3 to be treated or to be examined, may be positioned supine or lateral on the base support 1 and a tensile stress or tractive force FZ is applied to one or both of the lower extremities in order to distract one or both of the lower extremities 2. The tensile stress FZ may be initiated in the trunk-distant parts of the lower extremities, for example, at the feet, the shanks or the knees of the person 3. In general, a post 4 is used between the lower extremities 2 at the pelvis of the person 3, to take up the counteracting force to the tensile stresses FZ of the person 3. The post 4 is usually implemented in a round fashion and can be made in different diameters and have an upholstery.
Applying a tensile stress FZ creates an counteracting pressure transmitted over the post 4 to the pelvis, generally to a region between the ischial tuberosities. This pressure may damage the soft tissues located near the region of post 4. Examples of soft tissue injury are: the injury of outer genitals, such as of the penis and scrotum in the case of a male or the big and small labia in the case of a female. Also, local nerves may be injured, leading to dysaesthesia in the anal region, the perineal region, the scrotum, the penis, or the labia and the clitoris. More severe injuries lead to dysfunctions of the anal sphincter and the pelvic floor musculature so that important functions, like continence and sexuality, may be impaired for longer periods, often ranging from 4 to 6 weeks, or even permanently.
The tensile stresses FZ may lead to a tilting of the pelvis, with the ischial tuberosities as fulcrum, which stops only when the inferior part of the pubic symphysis of the pelvis together with the soft tissues that are interposed between the pelvis and the post 4 are pressed hard enough against post 4 to build up a sufficient counteracting force. This can cause additional soft tissue damage of for example the above mentioned outer genitals. Tilting the pelvis can also lead to a hyperlordosis of the lower spine which may cause indistinct postoperative lumbar pains, intervertebral disc damages, increased pressure at the nerve roots, intervertebral disc protrusions or damages to joint and osseous structures of the lumbar vertebral column.
Previous attempts to reduce these complications include reducing the force, the duration of traction as well as cushioning the post 4. Unfortunately, these measures only have limited success.
An object of the invention is to provide a pelvic support which avoids complications, that may arise due to the distraction of at least one lower extremity.